Last year was a bad one for Florida’s manatees, which experienced a record number of fatalities.

The Florida Fish and Wildlife Research Institute reported last month that more than 800 of the giant sea cows died in 2013, which was the highest total on record since the institute began researching the mammals 40 years ago.

The previous record for manatee deaths was 766 in 2010. At that time cold weather was largely blamed for the die-off.

Last year, a record number of manatees died from red tide (276) caused by high concentrations of algae in the ocean. Seventy-two were killed by watercraft and 36 died of cold stress.

One piece of good news to come out of the institute’s reporting was the number of manatee deaths caused by boats was only 71, which was a five-year low . Additionally, 14 manatees infected from red tide were able to be rehabilitated and released back into their marine habitat.